Class 3: Peptide Hormones Flashcards Preview

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Flashcards in Class 3: Peptide Hormones Deck (20):
1

Gonadotropins:

LH and FSH

2

FSH:

(From Pituitary): In ovary, stimulates development of ovarian follicles; In testes, regulates function of Sertoli cells (somatic cells within the testes that support sperm development) in the seminiferous tubules (compartments in which male gametes grow)

3

LH:

(From Pituitary): Secretion of steroid hormones from the gonads by binding to and stimulating steroidogenic cells (ovary & testes), regulates ovulation in females.

4

GnRH

(From Hypothalamus) endocrine communication via blood vessels to the pituitary

5

Exocytosis

delivery of the peptide hormone (or any other molecule) from out of the cell through secretory machinery (vesicles).

6

Endoplasmic reticulum :

Organelle where translation of proteins that are destined to leave the cell occurs.

7

Secreted protein

peptide hormones are secreted proteins that pass through the lipid bilayer and exit the cytoplasm to serve a function elsewhere in the cell.

8

Membrane protein:

cell membranes consist of a lipid bilayer and membrane proteins which accomplish vital biological functions. The ones we focused on in class were membrane receptor proteins which serve as the connection between intracellular and extracellular activity.

9

Differential gene expression

Only certain genes are transcribed in each cell type

10

Ligand :

molecule that binds

11

Steroid hormone receptor aka nuclear receptor:

Class of receptors: Androgen/ Estrogen/ Progesterone Receptors that consist of a DNA binding domain, a ligand binding domain (where T,E, P attach), and other “variable” factors. This receptor attached to the HRE (Hormone Response Element) & via a transcription factor begins transcription of DNA to RNA.

12

Transmembrane domains:

Positions the receptor in the plasma membrane, this domain is actually in the lipid membrane (hydrophobic/ lipophilic)

13

G-protein-coupled receptor:

Binds ligand (the peptide hormone); in the family: FSH-R, LH-R, GnRH-R

14

G-protein :

proteins closely coupled to the receptor, and initiate the intracellular signal transduction events.

15

Second messenger

Second messengers tend to be very small molecules. I.e. cAMP (Cyclic AMP)

16

Kinase:

enzymes that add phosphate groups to their substrates.

17

phosphorylation

the process of adding a phosphate group, phosphorylation changes the action of the protein

18

Signal Transduction:

Peptide hormone “first messenger”, attaches to molecule on the cell membrane initiating a reaction that produces a “second messenger” on the inside of the cell or allows for release of second messenger from a storage site out into the cytoplasm.

19

Basic Steps to Gonadotropin (LH/FSH) Induced Signaling:

1. Hormone Binds to the receptor (G-protein complex family) → activation of the G-protein
2. G-Protein activates Adenylate Cyclase (AC)
3. Activated AC generates Cyclic AMP (cAMP)
4. cAMP activates kinase protein kinase A (PKA) -which adds a phosphate group to the substrate ( phosphorylation).

20

Basic Steps to GnRH Induced Signaling:

1. Hormone Binds to the receptor (G-protein complex family) → activation of the G-protein
2. G-Protein activates Phospholipase C (PLC)
3. Activated PLC generates second messenger IP3
4. IP3 attached to receptor on ER & induces endoplasmic reticulum to release Calcium
5. Calcium activates kinase activity (which adds a phosphate group to the substrate – phosphorylation.)